Lecture

The generations of biochemists

Generalization of biochemistry: the study of composition, organization, structure and function.

Wohler started this whole business of biochemistry when he used ammonium cyanide to make urea --a product believed at the time to only be producible by living things (which ammonium cyanide obviously is not). This meant that man may be capable of doing reactions much like what occurs in the body.

Insert paper handout here

We can only look for life assuming it is similar to life on Earth (has "the thread of life").

There is only one thread we know, only one origin.

CHON = the elements here and elsewhere in the solar system.

Why is water so important, we'll we'll talk about that next week.

We cannot imagine life without water, so we assume it is necessary

Second most abundant (non-man-made) liquid is mercury (Hg).

Rock has been found that was made by bacteria that lives in sulfuric acid.

Europa: a moon of Jupiter; an enormous ball of ice which gravity causes it to crack, then fluid spews up through the cracks and we see that it is yellow. This makes us think it has organic material in it.

Even if water isn't really necessary for life, we probably won't recognize a form of life that doesn't use water.

Thread of Life

Time frame parameters for life

if it moves too slow we won't be around long enough to observe that it is dynamic; if it is too fast we don't see that it is self-controlled and purposeful. Either way, we probably wouldn't recognize forms of life at the extremes of a time scale.

we have to use catalysts to make our reactions happen at the correct rate, so we imagine that most forms of life do, also.

Information storage

we imagine that all forms of life need something like DNA to keep and pass along information.

Energy currency

most forms of life we know use ATP as the energy currency; we imagine that all living things have some sort of comparable currency.

Barrier

membranes, life probably needs them.

Limit to the size of single cells

There is an upper bound on the size of a single cell because of the rate of diffusion of water. If you assume that each cubic unit necessitates a certain amount of water, then as a cell expands, it becomes harder and harder to get enough water in and out of the cell to fulfill these water demands as surface area does not increase as rapidly as volume in expansion.

Polymers

we see that we have many different polymers and assume that most forms of life require such tools.